This invention relates to apparatus for forming elongated articles such as railroad spikes, bolts, nails and the like and more particularly to apparatus for forming such articles from a heated stock bar fed intermittently into the apparatus.
Heretofore in the art to which my invention relates, difficulties have been encountered with prior art devices used to form spikes and the like due to the fact that such devices produce spikes having end portions which are not formed to the exact shape and size required. Also, such spikes have offset heads which only marginally meet design specification requirements. Furthermore, these devices operate in multi-stage forging cycles to produce spikes in a very uneconomical and inconsistent manner, with the operation of such devices resulting in a substantial amount of down time and requiring considerable maintenance to maintain the apparatus in satisfactory working order.
Also, cumbersome gripping dies have been utilized heretofore to exert a constant gripping force to hold the heated stock bar in position while the tapered end portion and the offset head is formed. Spike body deformation is often experienced when soft or overheated stock bars are held by these dies since such bars require substantially less gripping force than the amount normally applied.
Massive compression dies have been used concomitantly with confining dies to form the tapered end portion as well as to maintain flat parallel sides for such end portion which are perpendicular to the tapered surfaces thereof. These confining dies do not adequately control the excessive bulging, swelling and flash usually associated with this operation thus resulting in the formation of tapered end portions which are not shaped properly.
Rotary dies, such as those disclosed in Great Britain Pat. No. 978, have also been employed in forming the tapered end portion for a spike. However, arcuate sides are formed by the cutting action of such dies thus resulting in only an approximately shaped tapered end portion being formed.
Another difficulty encountered is the positioning of the stock bar at the proper location to present the required amount of metal to form a spike head which meets design specifications. Also, devices heretofore employed form heads which are not uniform since they vary in length, width, thickness and the offset relationship of the head to the body of the spike.
The following U.S. patents disclose spike forming machines which utilize gripper dies for holding the bar, compressive dies to form the tapered end portion, and head forming dies: U.S. Pat. Nos. 319,587; 393,438; 415,494, 1,774,915; 2,507,817; 2,832,979 and 3,906,566.